Not really much performance. Maybe 2-3hp at peak rpm if you're lucky, BUT it is washable, and guaranteed for ever :)That makes it worthwhile to me. (Considering my 750il requires two air filters!!).

Get one. definitely recommended.

have one on the taurus sho and mustang 5.0 and they sound a little throatier in the growl. Never noticed it in my 750il because its quiet as a mouse at any rpm range.

: what do people think of the K & N air filter system? you know, the sporty-lookin one that replaces the BMW-installed air filter system. It promises a considerable change in performance, and that it is easy to clean and maintain. Thanks.